I was trying to establish communication between my PC (serial port) and Allen Bradley SLC 5/03 (channel 0- RS232 port). I did a autoconfiguration using RSLinx and selected RS-232 DF1 driver (Full duplex). No problem and I was able to see this PLC as node 1.

However, using RSLogix500, under Channel Configuration, I changed the driver from DF1 Full Duplex to DF1 Half Duplex Slave and dowloaded the new parameters.

Now, I have no communication with the PLC. When I do a autoconfiguration using RSLinx, an error message “Failed to find the baud and parity ! Check the cables and switch setting” pops every time.

The cable is OK. How can I establish the communication again ? Any suggestions ?

Thanks

 

In RSLinx you must to choose "DF1 Polling Master" driver because to communicate with a DF1 slave device your PC must to be DF1 Master.

Good Luck

 

Hi,
Try the PIC driver.

Jack

 

If you cant get a sucessful autoconfigure in RSLINX then you will have to clear the processor memory by removing the battery & shorting out the Vbb pads on the board. Remember this is a last resort as it will clear your program out completly.

Then do a auto configure in LINX & note the settings. Use these settings in your programe.

When you downloaded the programe that caused you to lose communications, did you see a warning that said you where about to lose communications?
If you ever see this cancel!! or you will be back in the same spot.

Hope this helps.

 

Hi Steven
Thanks for the quick response. It was the first time that I used this site and the responses have been great. Thanks to Gati and Jack as well but I went ahead with your suggestion as the PLC was a "Off Line" sitting in my office with no important program.

I cleared the memory with the default factory settings and I have now managed to "talk" with my SLC 5/03.

Many thanks and keep up the good work guys.

Diwaker

 

There are 2 options to solve this Problem, If u have PIC Module means communicate with PLC in ch2 and you can change the Ch1 Settings to Full Duplex. Otherwise Select the Halfduplex Drive in the RsLinx. If all the above things are not possible please remove the CPU and Discharge the Super Capacitor. It will set the Default Communication parametrs and u can commincate from RSLinx.

All the best
Bye
Guna

> I was trying to establish communication between my PC (serial port) and Allen Bradley SLC 5/03 (channel 0- RS232 port). I did a autoconfiguration using RSLinx and selected RS-232 DF1 driver (Full duplex). No problem and I was able to see this PLC as node 1.
>
> However, using RSLogix500, under Channel Configuration, I changed the driver from DF1 Full Duplex to DF1 Half Duplex Slave and dowloaded the new parameters.
>
> Now, I have no communication with the PLC. When I do a autoconfiguration using RSLinx, an error message “Failed to find the baud and parity ! Check the cables and switch setting” pops every time.
>
> The cable is OK. How can I establish the communication again ? Any suggestions ?
>
> Thanks

 

Since your SLC is now in Half-Duplex mode, your Full-Duplex RSLinx driver won't work.

The DF1 Half-Duplex Polling Master driver doesn't have an Autoconfiguration option, so you will have to manually set it for the correct serial port timing and framing options. You'll also need to put the half-duplex address of the SLC (I think you said it's Node 1) in the polled slave list for the half-duplex master.

Half-Duplex Polling is traditionally a difficult driver to get working right if you've set up specific handshaking parameters on the port but don't have the cables to match.... Don't change the SLC port settings unless you have the proper cable to match, or you'll find yourself draining the memory capacitor to get back online.